The present invention relates to a DC/DC converter. The DC/DC converter described in Japanese Patent Publication No. 5457559 (JP 5457559 B) is known. In the technology of JP 5457559 B, by controlling the switching operation of switching devices, the accumulation amount and the emission amount of energy to the reactor are controlled, voltage is stepped up from low voltage side to high voltage side, and power is transmitted, or voltage is stepped down from high voltage side to low voltage side, and power is transmitted. The DC/DC converter has a subject that the reactor enlarges and becomes heavy. In order to reduce the size and weight of the reactor, it is conceivable to reduce the voltage applied to the reactor and to reduce the inductance value required for the reactor. In the technology of JP 5457559 B, the first to the fourth switching devices connected in series are provided; and the charge and discharge capacitor, which is connected between the intermediate connection point of the first and the second switching devices and the intermediate connection point of the third and fourth switching devices, is provided. Then, by changing the duty factor of the first switching device and the duty factor of the second switching device in the opposite direction mutually, it is configured to control the voltage of the charge and discharge capacitor to the target voltage. By controlling the voltage of the charge and discharge capacitor to the target voltage, the voltage applied to the reactor is reduced and the size and weight of the reactor are reduced.